The present invention relates to improved method and apparatus for detecting sewing defects on a stocking toe closer, and more particularly relates to improvement in photoelectric detecting system of sewing defects, on an automatic stocking tow closer, such as skip sewing caused by thread breakage or abnormal engagement of a sewing needle with a thread, spot sewing caused by ill supply of the material, and foreign material inclusion.
On a known automatic stocking toe closer, automatic closing of the toe section of a stocking by sewing in general includes the following operational steps.
(i) In the first step, the welt section of a cylindrical material stocking is held by an operator and pneumatically sucked into a suction pipe with its toe section being on the leading side. PA1 (ii) In the second section, the pneumatic suction is interrupted and the welt section is placed over the end portion of the suction pipe. The remnant of the material stocking is positively and automatically rolled up in order to place the stocking inside out. The toe section to be closed is, however, left outside the suction pipe. PA1 (iii) In the third step, a pair of finger pieces annexed to the suction pipe is moved from each other in order to laterally stretch the toe section to be closed. Thereafter, the finger pieces holding the material stocking advance towards a sewing machine. PA1 (iv) The finger pieces holding the material stocking are moved laterally across the sewing position on the sewing machine so that a sew line is formed by the sewing machine along the fringe of the toe section. PA1 (v) In the fifth step, the finger pieces holding the toe-closed stocking recede from the sewing position and the stocking is returned to the original state. Thereupon, the pneumatic section is resumed in order to pass the complete stocking to the next operational station via the suction pipe.
No detection of the sewing result is included in the above-described process and the complete stockings are pneumatically passed to the next operational station whilst possibly containing some sewing defects. Operational troubles may often occur during sewing process whilst resulting in serious defects in the products, which considerably degrades the commercial value of the product and, when supplied on market, seriously blemishes the reputation of the producer.
Conventionally, detection of such sewing defects is carried out depending on visual inspection by the operators involved in the toe-closing process or by operators in the subsequent process or processes. This manual detection system requires increased labour and elongated operation time, both connecting to undesirable rise in production cost of stockings.